Motor control.



Witnesses.-

ZZZJi K Patented Sept. 2,1913.

Invent-0f: maX a)? Whit/r5, v

UNITED STATES PATENT omen MAX A. WRITING, OF SGHENECTADY, NEW YORK,ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATIONOF NEW YORK. v

MOTOR CONTROL.

1,071,84Q I Specification of Letters ifatent. Patented Sept. 2, 1913. I

Application filed October 18, 1 9 11. Serial No. 655,459.

To all whom it may concern: In order to prevent the electrically bper-Be it known that I MAX A. WHITING, a ated controller from cutting outthe startcitizen of the United States, residin at ing resistance andbringing the motor up Schenectady, county of gchenectady, tate to highspeed while the slack cable 'is'be- 5 of New York, have invented certainnew and ing taken up, I" provide a pair of magnets useful Improvementsin Motor Control, of G and ,H, the contacts of which are both which thefollowing is a specification. included in the circuit of the operatingMy invention relates to the control of windings of the startingcontroller, so that electric motors for operating winches, capthestarting controller is rendered inoperlo-stans, hoisting drums, etc.where at starting ative until both windings close their contheremay be acertain amount of slack cable tacts. The winding G is placed in seriesto be taken up before the load is thrown on, with the motor andtherefore is energized to the motor; and the object of my invention Witha current at all times proportional to is to provide controlling meanssuitable for the motor current, while the winding H is 15 motors drivingloads of'this character. connected in shunt to the'motor armature A Bymy invention I so arrange the motor and thereforeisenergized with acurrent control that the motor is prevented from which depends both onthe motor current reaching a high speed while the slack cable and on themotor speed. 'is being taken up, and to this end I provide, Theoperation is as follows; WVith tho ,20 in connection with 'the usualaccelerating motor at rest and switch fclosed, the main means orstarting controller, means for renwit h'F is clo d to admit c -rent tothe dering the controller inoperative to accelmotor. If the motor startsunder light load erate the motor until the load on the motor as is thecase if a slack cable is being taken rises to a predetermined am unt aup, the motor speed quickly rises to a value 25 My invention will bestbe understoodby high enough to cut the motor current down reference tothe accompanying drawings in to a small amount, so that, if the magnet G8 v which i is energized-sufiiciently to close its contacts Figure 1shows diagrammatically. a motor at the first instant when the switch Fis'closed, control system arranged in accordance with it soon opens itscont-acts as the motor speed, 30 my invention; and Fig. 2 shows amodificarises. Magnet His designed so that it does tion thereof. .notclose its contacts until after'the motor In the particular embodiment ofmy r in armature A has reached a high enough speed -vention shown in thedrawing A represents to cause magnet G to drop its contacts. thearmature and B the field winding of an Thus during this firstacceleration and op- 35 electric motor of the commutatortype, suchoration under light load the starting conaS a series wound directcurrent motor. The troller remains inoperative. -The magnet motor isshown provided with an automatic H retains its contacts closed with acom electrically operated step by step controller paratively smallcurrent in the winding, so

, for gradually accelerating the motor. This that whenthe slack cablehasbeen taken up 40 controller which is of a type well known in and theload comes on to the motor, slowing the art comprises startingresistances C, the motor down suiilciently to draw enou h magneticallyactuated switches-or contactorscurrent to energize winding G, wmding H Dfor cutting out theresi'stances step by still holds its contacts closedso that the step, and current limitin devices E for precircuit for thestarting cont-roller windings 7 1b venting the resistance rom being cutout is then completed. The left hand contactor too fast, or in otherwords, for insuring. D consequently closes, short-clrcuitmg one properacceleration. 7 section of. the starting resistance C, and,

F represents the main switch for connectafter the motor current hasfallen a Sui-- i th motor to the source of siipply and f ficient. amountto allow the contacts con- 50 represents a switch in the controlcircuit, trolled, by winding E to close, the "second that is, in thecircuit of the operating windcontactor D operates, and so on until allings of the contactors D. the starting resistance is cut out. Thus theThe arrangement thus for described is starting controller is renderedoperative l i one which is well known in the art. only when both themotor current and the motor speed rise to predetermined amounts, but,when thus rendered operative, it acts precisely as the usual automaticcontroller operates when. the motor circuit is first closed.

The operation above described is that which takes place under normalstarting renditions. It may sometimes occur, however, that the motor maybe required to start under load, that is, with no slack cable, in whichcase the motor speed and armature voltage might not rise sutii'cientlywith all the starting resistance in circuit to cause relay Hto close itscontacts. lo provide for the operation of the starting controller undersuch special conditions where relavII does not become energized, Ipropose to use a switch it in shunt to the contacts of relay H. Thisswitch may be of the push button type, that is, a normally open switchwhich can be closed and kept closed only as long as the operator keepshis hand on it. For starting under load, the switch 71- is closed whichcloses the control circuit tor the starting controller and enables it tocut out the resistance. As the motor speeds up, thearmature voltagerises so that relay ll closes its contacts and switch It may then bereleased.

Fig. 2 shows a modification which is identical with the arrangementshown in Fig. l with the addition of acircuit closed by relays G and Hwhich acts further to limit the motor speed on light load. As has beenexplained, when the motor is running under light load relay G isdeenergized and relay H energized. Under these conditions a shuntcircuit, including a resistance J, is

T closed around the motor armature. and

series as a further limitation on the motor speed at light load. Thisarrangement may advantageously be employed where the amount of startingresistance C is not so great but that the motor could run up to speedunder no load, with all the starting resistance in circuit, if the shuntcircuit were not employed.

ular form of starting controller shown in the drawings; furthermore, themeans for rendering the controller inoperative until the proper time iscapable of many difi'erent embodiments. Consequently, I do not desire tolimit myself to the particular construction, connections and arrangementof parts shownand described, but aim in the appended claims to cover allmodifications which are within the scope of my inven- 1 tion.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,

1. In combination with an electric motor,

automatic acceleratin means therefor. a magnet winding energlzed by acurrent proportlonal to the motor current, and means theparticrespectively t6 the motor current and to the 7 motor armaturevoltage, and means forrendering said controller operative only when thecurrents in both magnet windings rise to predetermined amounts.

3.- In combination with an electric motor of the commutator type, astarting resistance therefor, an electrically-operated'controller forcutting out said resistance stepby-step, two sets of contactscooperating to render said. controller operative, and apair of magnetwindings energized by currents proportional respectively to the motorcurrent and to the motor armature voltage and controlling said contactsto render the controller operative only -when both currents rise topredetermined amounts.

4. In combination with an electric motor,v an electromagnetic controllerfor gradually accelerating the motor, and means for ener-' gizing saidcontroller only when both the motor current and motor speed rise topredetermined amounts.

5. In combination with an electricmotor of the commutator type, acontroller for gradually accelerating the motor, a pair of magnetwindings energized by currents proportional respectively to the motorcurrent and to the motor armature voltage, and means for limiting themotor speed to a comparatively low amount until the currents in bothwindings! rise to predetermined amounts. 6. In combination with anelectric motor, automatic accelerating means therefor, and means forrendering said accelerating means inoperative and closing a shuntcircuit around the motor until the load on the motor rises to apredetermined amount.

7. In combination with an electric motor of the commutator type, acontroller for,

gradually accelerating the motor, a pair of magnet windings energized bycurrents proportional respectively tothe motor current and to the motorarmature voltage, and means for closing a shunt circuit around the motorwhen the current in the first magnet is below, and the current in theother magnet above, predetermined amounts.

8. In combination with an electric motor of the commutator type,automatic acceler ating means therefor, and means torrendering saidaccelerating means operative only when the motor current and the motor 1armature voltage both rise to predetermined amounts, and, for closing ashuntcircuit around the motor when the motor current is above?predetermined amounts.

operative only when both the motor current Y and motor speed rise topredetermined .Wltnesses:

nos-1,640 3 below, and the motor armature voltage, below and the motorspeed 'above predeter- 1'0 mined amounts. 1 9! n combination with anelectric motor, In witnesswhereof, I have hereunto set automaticaccelerating means therefor, and my hand this 17th day of October, 1911.means for renderingsaid accelerating means MAX VVHITING.

' BENJAMIN B. HULL,-

amounts, and for closing a shunt circuit HELEN ORFDRD.

around the motor, when the motor urrentis Copies 01 this patent may beobtained 101' five gents each, by addressing the Commissionerof Patents,

' Washington, D. G.

